sl@0: /* S_FLOOR.C
sl@0:  * 
sl@0:  * Portions Copyright (c) 1993-2005 Nokia Corporation and/or its subsidiary(-ies).
sl@0:  * All rights reserved.
sl@0:  */
sl@0: 
sl@0: 
sl@0: /* @(#)s_floor.c 5.1 93/09/24 */
sl@0: /*
sl@0:  * ====================================================
sl@0:  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
sl@0:  *
sl@0:  * Developed at SunPro, a Sun Microsystems, Inc. business.
sl@0:  * Permission to use, copy, modify, and distribute this
sl@0:  * software is freely granted, provided that this notice 
sl@0:  * is preserved.
sl@0:  * ====================================================
sl@0:  */
sl@0: 
sl@0: /*
sl@0: FUNCTION
sl@0: <<floor>>, <<floorf>>, <<ceil>>, <<ceilf>>---floor and ceiling
sl@0: INDEX
sl@0: 	floor
sl@0: INDEX
sl@0: 	floorf
sl@0: INDEX
sl@0: 	ceil
sl@0: INDEX
sl@0: 	ceilf
sl@0: 
sl@0: ANSI_SYNOPSIS
sl@0: 	#include <math.h>
sl@0: 	double floor(double <[x]>);
sl@0:         float floorf(float <[x]>);
sl@0:         double ceil(double <[x]>);
sl@0:         float ceilf(float <[x]>);
sl@0: 
sl@0: TRAD_SYNOPSIS
sl@0: 	#include <math.h>
sl@0:         double floor(<[x]>)
sl@0: 	double <[x]>;
sl@0:         float floorf(<[x]>) 
sl@0: 	float <[x]>;
sl@0:         double ceil(<[x]>) 
sl@0: 	double <[x]>;
sl@0:         float ceilf(<[x]>) 
sl@0: 	float <[x]>;
sl@0: 
sl@0: DESCRIPTION
sl@0: <<floor>> and <<floorf>> find 
sl@0: @tex
sl@0: $\lfloor x \rfloor$, 
sl@0: @end tex
sl@0: the nearest integer less than or equal to <[x]>.
sl@0: <<ceil>> and <<ceilf>> find 
sl@0: @tex
sl@0: $\lceil x\rceil$,
sl@0: @end tex
sl@0: the nearest integer greater than or equal to <[x]>.
sl@0: 
sl@0: RETURNS
sl@0: <<floor>> and <<ceil>> return the integer result as a double.
sl@0: <<floorf>> and <<ceilf>> return the integer result as a float.
sl@0: 
sl@0: PORTABILITY
sl@0: <<floor>> and <<ceil>> are ANSI.
sl@0: <<floorf>> and <<ceilf>> are extensions.
sl@0: 
sl@0: 
sl@0: */
sl@0: 
sl@0: /*
sl@0:  * floor(x)
sl@0:  * Return x rounded toward -inf to integral value
sl@0:  * Method:
sl@0:  *	Bit twiddling.
sl@0:  * Exception:
sl@0:  *	Inexact flag raised if x not equal to floor(x).
sl@0:  */
sl@0: 
sl@0: #include "FDLIBM.H"
sl@0: 
sl@0: static const double huge = 1.0e300;
sl@0: 
sl@0: /**
sl@0: Round down value.
sl@0: Returns the largest integer that is less than or equal to x 
sl@0: @return   Floor of x.
sl@0: @param x Floating point value
sl@0: */	
sl@0: EXPORT_C double floor(double x) __SOFTFP
sl@0: {
sl@0: 	__int32_t i0,i1,j0;
sl@0: 	__uint32_t i,j;
sl@0: 	EXTRACT_WORDS(i0,i1,x);
sl@0: 	j0 = ((i0>>20)&0x7ff)-0x3ff;
sl@0: 	if(j0<20) {
sl@0: 	    if(j0<0) { 	/* raise inexact if x != 0 */
sl@0: 		if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */
sl@0: 		    if(i0>=0) {i0=i1=0;} 
sl@0: 		    else if(((i0&0x7fffffff)|i1)!=0)
sl@0: 			{ i0=0xbff00000;i1=0;}
sl@0: 		}
sl@0: 	    } else {
sl@0: 		i = (0x000fffff)>>j0;
sl@0: 		if(((i0&i)|i1)==0) return x; /* x is integral */
sl@0: 		if(huge+x>0.0) {	/* raise inexact flag */
sl@0: 		    if(i0<0) i0 += (0x00100000)>>j0;
sl@0: 		    i0 &= (~i); i1=0;
sl@0: 		}
sl@0: 	    }
sl@0: 	} else if (j0>51) {
sl@0: 	    if(j0==0x400) return x+x;	/* inf or NaN */
sl@0: 	    else return x;		/* x is integral */
sl@0: 	} else {
sl@0: 	    i = ((__uint32_t)(0xffffffff))>>(j0-20);
sl@0: 	    if((i1&i)==0) return x;	/* x is integral */
sl@0: 	    if(huge+x>0.0) { 		/* raise inexact flag */
sl@0: 		if(i0<0) {
sl@0: 		    if(j0==20) i0+=1; 
sl@0: 		    else {
sl@0: 			j = i1+(1<<(52-j0));
sl@0: 			if(j<i1) i0 +=1 ; 	/* got a carry */
sl@0: 			i1=j;
sl@0: 		    }
sl@0: 		}
sl@0: 		i1 &= (~i);
sl@0: 	    }
sl@0: 	}
sl@0: 	INSERT_WORDS(x,i0,i1);
sl@0: 	return x;
sl@0: }